Black smoke, to some degree, is normal for any diesel. It's going to be a matter of how much, and what the engine is doing when it 'puffs.' It's nothing to worry about at any time, it may mean some testing and adjusting, and on rare occasions most of us have thought it quite humorous to 'dust' a tailgater.

Come back around, tell us more about it, let's see how bad it really is.

Best Regards,
Jim